Lesson video

This lesson is called "Agriculture and Habitat Loss" and is from the unit Climate change and biodiversity.

Hi there.

My name's Mrs. McCready.

And I'm here to guide you through today's lesson.

So, thank you very much for joining me today.

In our lesson today, we're going to explain how growing crops for food is linked to the loss of habitats and a decrease in biodiversity.

So, in our lesson today, we're gonna come across a number of keywords and they're listed up here on the screen for you now.

You may wish to pause the video to make a note of them, but I will introduce them to you as we come across them.

So, in our lesson today, we're going to first of all have a look at how food production and habitat loss are interlinked before we consider how we can reduce habitat loss through agriculture.

So, are you ready to go? I certainly am.

So, let's get started.

There are just over 8 billion people living on earth.

And that is a lot of people to have to feed.

Now, the food that we eat comes from either crops, which are edible plants and fungi or animals that have eaten those crops that we then eat.

So, whatever food we are feeding ourselves has to come from one of these two sources.

Either from edible crops or from animals that ate those crops.

Now, producing all of that food depends upon agriculture.

There are very, very, very few individuals within the entire world who are able to produce all of their own food entirely on their own without anybody else helping.

So, you may well have a greenhouse or an allotment where you produce some of your food, but you will need to buy food from the supermarket or from Farmers' markets to supplement that.

And that food will have been produced through agriculture.

Now, agriculture includes using land to raise farm animals that we then eat or to grow crops to feed those animals, or to grow crops that we eat directly.

All of those different things are forms of agriculture.

So, let's have a look at how the population has changed over the course of the last 12,000 years.

So if we go back to 10,000 years BCE, we can see that there were only 4 million people living on earth in total.

That's half the total population of London today.

And that was all of the people living on the entire planet.

Fast forward to the Year 0, and there were 190 million people living on earth by that stage.

The 1 billion threshold was passed in 1804, and that has increased very, very quickly ever since.

2 billion in 1928, 5 billion in 1987, 7 billion in 2011.

And 11 years later, the 8 billion mark was reached in 2022.

So, there are now more than 8 billion people living on earth.

So, what can we conclude from the data in this graph? Well, we could first of all say that the population was relatively small for most of the period of the last 12,000 years.

And in the last 200 years, this increase has become very rapid.

Now, this means that as the human population size increases, we are going to need more food to feed everyone.

And that means that more land will need to be used for agriculture.

So, who is correct? Andeep says, "The human population is going up, so we have to use more land for food production." Sam says, "The human population is decreasing, so less land is needed for producing food." And Izzy says, "The human population is relatively small now, so we don't use much land for agriculture." Who is correct? I'll give you five more seconds to think about it.

Okay, so you should have said that Andeep is correct.

The human population is increasing and that is requiring more land for food production.

Well done.

So, we have to use more land for agriculture, and that requires converting land from a different purpose into agriculture.

And often this requires deforestation.

So, deforestation is the removal of forest land and converting it into another use such as for agriculture or maybe for housing developments.

So, forest land is a very rich and diverse habitat.

There are lots of different animals and plants living within forests.

And if we cut down the trees or burn them to deforest that land, we will then remove all of those different species of plants and animals that are living in the forest because the forest will no longer exist.

And if we then replace it with farmland, there will only be a few species growing in a space where there were thousands of different species.

And most of those species will be the crops that we are growing, maybe a few weeds, but that's about it.

So, the number of species will be significantly reduced through deforestation for agricultural purposes.

Now, forests are very important habitats.

They provide habitat for a wide variety of different plants, animals, and fungi.

And there are lots of different types of forest across the world, each with their own unique set of organisms. Animals, plants, and fungi living within that space.

Now, this is habitat for lots of different purposes, as well as lots of different species.

So, this provides shelter, shelter from the weather and the temperature and also shelter from predators.

It also provides places for those animals and plants to reproduce.

And of course, it provides food for them as well.

If we deforest that land, if we convert it into farmland or into another purpose, we first of all, lose that original habitat.

All of those species are removed.

And if we're converting forest land into farmland, then there are very few species remaining because their habitat has gone.

So, many birds can't survive in farmland because there are no trees, for instance.

And this means that we have not just deforested the land, but we have also destroyed a really important habitat for many other species.

It's not just the loss of the trees, but it's the loss of all of the other organisms living in that forest who have gone as well.

So, let's look at an example of a cause of deforestation.

Palm oil.

Now, producing palm oil is a major cause of deforestation.

What happens is very rich forest land is chopped down and burnt and converted into growing certain types of palm trees so that palm oil can be extracted from them.

And that palm oil is used in a vast array of different things, including many different types of food.

Crisps, ready meals like pizzas and donuts and cookies, chocolate, ice cream, but it also comes up in other products as well that are made in industry, such as shampoos and body washes as well.

So, palm oil is found all over the place and in many, many different food sources in particular.

So, when forest land is being converted to grow palm trees, we can see in the picture on the screen where the forest was, where it has been deforested, so where the forest has been cut down, and then where it has been converted into plantations where the palm oil trees have been planted in these very regular neat rows.

So, palm trees are grown in large plantations and planted after forest has been removed by being cut down and burnt.

Now this, as I say, has significant knock-on implications for the species of organisms, the animals and the plants that were living in that forest before it got torn down.

And species such as the Sumatran Orangutan are now critically endangered because of the loss of their habitat due to deforestation for palm oil production.

So, these beautiful creatures now no longer have habitat to live in because those forests have been removed and destroyed so that palm oil can be grown instead.

So, let's have a look at this graph.

We can see the habitable land on the left and the years from 1700 to just after the year 2000 on the X axis on the bottom.

The very dark section A is land for towns and cities.

The brown section B is land being used for growing crops.

The yellow section C is land being used for rearing animals.

The light green section D is grassland.

And the dark green section E is forest land.

So, is this statement true or false? Since 1700, humans have destroyed almost a third of the world's forest for agriculture.

So, have a look at the value for forest as a percentage of the earth's habitable land from 1700.

Compare it to the value just after 2000.

How much of the forest has been destroyed in that intervening 300 or so years? Okay, so you should have said that that is true.

But can you explain why? Perhaps you've already worked this out.

So, you should have said that in 1700, 53% of the world's land was forest.

Whereas in 2024, it is now 37%.

So, this is a reduction of 16%.

Now, if we times 16 by 3, we get 48.

And that means that is almost a third of 53%.

That was forest present in 1700.

Well done if you managed to calculate that.

Now, palm oil, as I've said, is used in many, many common foods.

And if you look at the food labels, you'll see palm oil crops up in many different foods.

And I've also said that producing palm oil is a major cause of habitat loss due to deforestation.

Many millions of hectares of forest land have been deforested and converted into palm oil plantations.

Now, the table here shows how greenhouse gas emissions caused by deforestation vary across the production of various different oils.

Soybean oil, palm, sunflower, and olive oil.

So, what I'd like you to do by way of summarising this first part of the lesson is to write some guidance to a shop owner who wants to sell forest-friendly snacks.

What advice would you give them? So, pause the video and come back to me when you are ready.

Okay, let's review your work.

So, I asked you to write some guidance to the shop owner who wants to sell forest-friendly snacks.

And perhaps you have said that they should avoid selling snacks that can contain palm oil, such as crisps, pizzas, donuts, biscuits, chocolate, and ice cream.

And if they do sell these snacks, they should try to sell brands that have been made with sunflower oil or olive oil instead of palm oil or soybean oil because producing sunflower oil and olive oil involves less deforestation and produces lower greenhouse gas emissions than palm and soybean oil.

Well done if you've got those points.

Do add to your work if you need to.

Okay, let's move on to have a look at how habitat loss could be reduced through agriculture.

So, let's first of all consider what biodiversity is.

So, biodiversity is the range of different species that are living within an ecosystem.

And the more biodiverse an ecosystem is, the greater the number of different species that are living within that space.

So, the ecosystem is the habitat and all the living organisms present within it.

And the biodiversity is a description of how many different species are present within that ecosystem.

Now, forests have very important habitats for a great range of different species, including plants and animals and fungi.

And because of the wide variety of different species living within forests, they have a high biodiversity.

So, forest land is a rich and biodiverse ecosystem because it houses lots of different species.

And all of this species that are living within a forest depend upon each other in one way, shape, or form to survive often through food chains, but perhaps through other reasons such as the provision of shelter, such as trees providing shelter for birds and insects for instance.

Or through space for reproduction to happen, such as little pools of water where frogs might be able to reproduce.

So, all of the different species living within a forest depend upon each other in order to survive.

Now, if we deforest that forest, if we cut that forest down, we remove all of that biodiversity.

We remove shade and shelter, and we disrupt the food chains that exist within that forest land.

Many of the animals and the plants that are living in that forest will not be able to continue to survive because their habitat will have been destroyed.

And if we replace that forest land with farm fields, then although there are still crops growing, there are still plants growing within that space, there is only one species now growing.

The crop itself rather than that rich and diverse set of species that were growing in the forest before it was cut down.

That means that the biodiversity of the farmland is low.

There are very few species of organisms, plants, animals, and fungi.

And therefore, there is not a great mix of these different organisms, and therefore, biodiversity is low.

So, we can conclude that the conversion of land to agriculture is a major cause of habitat loss and of biodiversity loss.

Many of the organisms, the plants, the animals, the fungi that were present within the forest can no longer survive.

And some of them may even go extinct.

If their habitats are so totally destroyed that there is no habitat left for them to live in, then they may have nowhere to live, and therefore, the species may die out completely and therefore, go extinct.

Now, some of the species that are threatened with extinction include a great range of pollinators.

And pollinators are essential for enabling food to be produced because if pollen isn't moved from one flower to another by pollinators such as bees and insects and birds and bats, then the plants that require that pollination to happen cannot have their eggs fertilised by the pollen and cannot make seeds ready for the next generation.

So, threatening pollinators also threatens the ability for plants to survive as well.

And this doesn't just affect the plants within the forest because if the forest was still there, then those pollinators would still be there.

But if we've cut down the forest and replaced it with farmland, then the places where pollinators may have lived, such as in trees and in tree bark have been destroyed, and therefore, there are now no longer any pollinators to pollinate the farmland.

So, it's actually counterproductive to remove all of this forest land to produce crops if we end up losing the animals required in order to make the crops grow.

So, let's check our understanding with this.

What I'd like you to do is to complete the sentences using only the words decrease or increase.

So, I'll give you five seconds to review the sentences before we go through them.

Okay, let's check our answers.

Deforestation causes a decrease in the number of trees.

The number of other plants species is likely to decrease.

The number of animal species is likely to decrease.

And the biodiversity of the area is likely to decrease.

Did you use decrease in all four of those spaces? Well done if you did.

So, what can we do to reduce habitat loss due to agriculture? Because this is a pretty bleak picture that I've painted so far.

Well, there are lots of things that can be done to improve habitats and to reduce habitat loss.

First of all, we need to make some positive land use changes or ecosystem restoration to help replace lost habitat and lost biodiversity.

Now, we can do that through reforestation.

We can grow trees on land that is now no longer being used for agriculture and regrow those forests in the hope that as the forest establishes itself again, so the other species will return as well.

We could also rewild.

This is about allowing native species to regrow on parts of farmers' land.

So, around the edges of crop fields, for instance, where the crops are still being grown, but quite large portions of land are given over two rewilding.

Now, over the last 20, 30 or so years, there have been great initiatives from the EU and the UK governments to allow and enable farmers to rewild parts of their farmland to improve biodiversity.

But these strategies of reforestation and rewilding only replace a small portion of the habitat that has been lost to deforestation for agriculture.

And therefore only go very small way to helping to restore the biodiversity that has been lost through that deforestation.

So, what else could we do in order to have a greater impact on habitat loss to improve it? Well, the biggest thing that we can do is to change our diets.

If we go back to that graph we were looking at a little bit ago, we can see that the section C on the graph in yellow is the proportion of land used for rearing animals.

And you can see how that proportion has increased substantially over the last 320 years.

And so, a lot of habitat has been lost because land has been converted so that animals can be reared instead.

So, if we all eat less meat, this will reduce the demand for land used for rearing animals, and therefore, firstly reduce further deforestation.

And secondly, enable rewilding and reforestation projects to happen as well.

It also means that the land that would have been used to grow animals, to rear animals can instead be used to grow crops that feed us.

So, which strategy is likely to have the biggest impact on replacing lost habitat and lost biodiversity? Many people eating less meat, reforestation, or rewilding? I'll give you five seconds to decide.

Okay, so the strategy that is going to have the biggest impact is many people eating less meat.

Well done if you chose that.

Okay, let's summarise this part of the lesson by considering a farmer who is rewilding some of their land, which was once used to grow wheat.

Now, they find that native plants, including flowers and trees are regrowing on this land.

And what I would like you to do is to explain how this will help to restore lost biodiversity.

So, pause the video and come back to me when you're ready.

Okay, let's check your work.

So, how will rewilding help to restore lost biodiversity? Well, you might have said that the original habitat will be restored or at least partially restored, and this will provide shade, shelter, and a place to reproduce, and also food for many species, including flowers that will support pollinators.

You might also have said that this will enable many more species to live in the area, and this will increase the biodiversity of the area.

Well done if you've included all of those points.

And do add to your work if you need to.

Okay, we've come to the end of our lesson today.

And what we have seen is that we have to produce a lot of food to feed the increasing human population.

And therefore, we need a lot of land for agriculture, which includes rearing animals and growing food for animals and for us.

Now, converting land for agricultural use is one of the major causes of deforestation worldwide.

And deforestation, so the cutting down of trees results in habitat loss for many species within the ecosystem which has been affected.

Converting land for agricultural use is a major cause of habitat loss and of biodiversity loss because of the loss of all of the different species that were growing within the forest and can now no longer grow there because the forest doesn't exist anymore.

Now, strategies that can help to reduce habitat loss and biodiversity loss include changing diets to eat less meat, and also positive land use change, which includes things like reforestation and the rewilding of agricultural land.

So, I hope you found this interesting and perhaps have come away with some ideas about things that you can do to help reduce habitat loss.

So, thank you very much for joining me today, and I hope to see you again soon.

Bye.